Re: CPU waiting for I/O in Exadata Database Node

  • From: Stefan Koehler <contact@xxxxxxxx>
  • To: Oracle Mailinglist <oracle-l@xxxxxxxxxxxxx>, exriscer@xxxxxxxxx
  • Date: Wed, 23 May 2018 12:35:05 +0200 (CEST)

Hello Cheng,
please be also aware that iowait might not represent what you think.

* https://support.hpe.com/hpsc/doc/public/display?docId=c02783994
* http://veithen.github.io/2013/11/18/iowait-linux.html

Best Regards
Stefan Koehler

Independent Oracle performance consultant and researcher
Website: http://www.soocs.de
Twitter: @OracleSK

Ls Cheng <exriscer@xxxxxxxxx> hat am 22. Mai 2018 um 19:28 geschrieben: 

Hi 
 
I am observing quite high CPU waiting for I/O in Exadata Database Nodes 
(vmstat output). but from iostat there no waits at all (which is obvious 
since heavy I/O is done through infiniband). 
 
Anyone know what can be the CPU waiting for? 
 
Thanks
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